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GeForce 7950 GT: Closer Look

PCB Design and Cooling System

Just as it was the case with the GeForce 7900 GS, the PCB design of the GeForce 7950 GT is an exact copy of the GeForce 7900 GT that we described in our earlier review.

Although the cards are made using the same reference PCB and carry identical coolers, Nvidia’s partners have more freedom with the GeForce 7950 GT than they had with the GeForce 7900 GTX and 7950 GX2, and original models have appeared on the market. For example, XFX’ version of the GeForce 7950 GT has a black PCB and a passive cooler. There also exist a number of pre-overclocked versions of the card.

The main frequency of the GeForce 7950 GT GPU that all its units, save for the vertex processors, are clocked at is 550MHz. The frequency delta is the same as with other Nvidia’s cards on the G71 chip, namely 20MHz. It means that the vertex processors are clocked at 570MHz. This is a rather big step forward over the GeForce 7900 GT, and the use of the old cooler may seem indiscreet. We will check this out in our power consumption tests.

The GeForce 7950 GT carries eight 512Mb GDDR3 chips (Infineon HYB18H512321AF-14) for a total of 512 megabytes of graphics memory. The chips work at 2.0V voltage and have a rated frequency of 700 (1400) MHz. This is indeed the frequency the chips are clocked at by the card, providing a bandwidth of 44.8GB/s across a 256-bit bus. The memory already working at its rated frequency, there’s little hope it will do well at overclocking, although there may be exceptions (for example, we once managed to achieve a 20% memory frequency growth from our GeForce 7900 GS).

The card has a standard connector configuration: two DIV-I ports capable of working in dual-link mode and a universal 7-pin S-Video/YPbPr port. Every GeForce 7950 GT supports HDCP (the card features a special chip that stores keys to decode protected HD video content).

The reference cooler of the GeForce 7950 GT consists of a copper base and a folded copper sheet glued to it. It is equipped with a 45mm 0.19A fan that has a two-wire connection to the PCB. The cooler, covered with a plastic casing, is fastened to the card with four spring-loaded screws and takes heat off the graphics core only; the memory chips get no cooling at all. Dark grey thermal grease is used as a thermal interface between the cooler and the GPU die.

There could not be any apprehensions about that rather simple cooling solution at GPU frequencies about 450MHz due to the low heat dissipation of the G71 chip, but it may prove inadequate for a frequency of 550MHz. Some graphics card manufacturers, particularly EVGA and XFX, seem to share this opinion as they equip their versions of the card with more advanced coolers.

 
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